does anyone know where on earth i can finda detail of requirements for writting a sop contained by gmp standards?thanx?

I've read SOPs (Standard Operating Protocols) for different companies I've worked for and they are not based on any sort of requirement that I know of, it's newly a list of steps that should rightfully be done when something is being produced surrounded by a lab under GMP (Good Manufacturing Practice). Also, they contain trade secret and we were warn not to make copies of them or rob them home, just to sign the tabloid that acknowledges that we read them, so it may be rock-hard to find good examples that are not confidential.